1. Field of the Invention
The present invention relates to a rolling element retainer, and more particularly to a rolling element retainer for a linear guideway.
2. Description of the Prior Art
Linear guideway with rolling element retaining chain has been widely used on all types of precision sliding equipment, such as numerical control machine, automatic welding machine, transportation facilities, and the like. A general linear guideway is usually assembled in such a way that the rolling elements move endlessly along an annular rolling path, while a linear guideway with rolling element retaining chain must be provided in the whole circulating path with receiving groove for the passage of the linking portion of the rolling element retaining chain. However, the receiving groove of the whole circulating path is not a unitary structure but made up of several separate parts, consequently, a height difference will be caused at the connection between the separate parts, this will adversely affect the movement of the linking portion of the rolling element retaining chain.
As shown in FIGS. 1 and 2, a sliding block 11 is mounted on a conventional linear guideway with rolling element retainer, the linear guideway generally includes a loading retainer 12 and a return retainer 13. The loading retainer 12 and the return retainer 13 are provided with a receiving groove 121, 131, respectively, for the passage of a rolling element retaining chain 14. The rolling element retaining chain 14, as shown in FIG. 3, comprises a linking portion 141 on which are disposed a plurality of spacers 143 for separating the rolling elements 142 from one another.
The connection between the receiving groove 131 of the return retainer 13 and the receiving groove 121 of the loading retainer 12 is not specially designed, when the linking portion 141 of the rolling element retaining chain 14 moves to the loading retainer 12 from the return retainer 13, some problems are likely to take place, they are to be explained as follows:
First, the rolling element retaining chain 14 of the conventional linear guideway is usually made of flexible plastic so as to make it easier to go through return retainer 13. However, when approaching the connecting portion between the return retainer 13 and the loading retainer 12, the linking portion 141 will abut against the outer periphery of the receiving groove 131 because of elasticity, as shown in FIG. 4, in which, the rolling element retaining chain 14 is simplified by a rectangular strip. When moving to the connecting portion, an angular deviation will be caused such that the rolling element retaining chain 14 will not move in the predetermined direction of the blank arrow, but will move in the real direction as indicated by the solid arrow.
Second, the loading retainer 12 is assembled with other components normally by means of pins, however, height difference will take place between the receiving groove 131 of the return retainer 13 and the receiving groove 121 of the loading retainer 12 due to the fitting and manufacturing tolerance.
Based on the above-mentioned reasons, with reference to FIG. 6, when the linking portion 141 of the rolling element retaining chain 14 passes through the receiving groove 131 of the return retainer 13, it will hit the edge of the receiving groove 121 of the loading retainer 12, such a running module will cause an unstable running of the rolling elements.
To solve this problem, JP Patent No. 3,349,238 discloses a linear guideway, in which, the connecting portion of the circulating path is not at the abutting surface between the return retainer and the loading retainer, so that the rolling elements can get through the connecting portion smoothly by adjusting the moving direction. However, this design improves the difficulty of manufacturing.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.